Civil servants fear a plan to give them the option of working an extra five years beyond the retirement age of 60 could give rise to favouritism.
The Civil Service Bureau on Thursday embarked on a public consultation on whether to increase the official retirement age for new staff from 60 to 65, citing an ageing population and shrinking workforce.
If implemented, new staff would be required to work to 65, while current staff would be given the option of staying on for up to five years after hitting 60 if they so wished - and providing they pass an annual assessment.
Some civil servants fear that the proposal - in particular the requirement for an annual assessment - will allow bosses to play favourites over which employees will be allowed to stay on.
Deputy Secretary for the Civil Service Eddie Mak Tak-wai said he had "heard our colleagues sharing their concerns" about the assessments.
However, he said it was just an extension of the current practice, whereby department heads could allow retiring staff to stay on for up to 90 days. More than 300 such cases were handled in the last financial year.
Federation of Civil Service Unions chairman Leung Chau-ting challenged Mak's assertion.
"How one's superior sees him or her will be the key issue," he said. "Everyone knows this is very subjective. No one can exclude the weight of personal feeling. People build their own cliques, there could be favouritism."
Leung argued that the assessments should take place every two to three years, so that "the employees need not feel psychologically threatened".
The proposals have been welcomed by the General Chamber of Commerce and the Federation of Hong Kong Industries.